I personally have never found a link between my static capabilities and kicking technique.A lot of good kickers can't achieve the splits and many who can do the splits can't kick to head height.
If you've read stretching scientifically you will have seen the "hand kicking" method of dynamic stretching.This is performed so your leg doesn't slow down at the extreme range of the stretch.I've found that the more i did this the more my mind/body got used to it,and so my kicks don't slow down(giving the effect of more speed which is what you say you're after).

The only benefit static stretches would have is not what you perform but how you perform them.Isometric stretches focusing on the strength gains will make you stronger(and more injury resistant) in the extreme ranges of motion.This will also have the phsychological effect of telling yourself you can handle higher/more rapid kicks without risk of injury.